I honestly think the opposite, or maybe both are possible at once, people have gotten so used to fat people that they seem to think people at perfectly healthy weights are underweight.
And it's not all about the fat. People have become horribly weak because of their sedentary lifestyle. Sit at a desk for 8h, sleep 8h, sit on the couch for 2h for entertainment, sit while eating for 1h.
And it's perfectly understandable that people want to take care of their body more than they care about other things. It's the only thing that is truly theirs and no amount of money can fix it if you don't take care of it.
In my case, I was well past the "obese" point on the BMI scale, but not "morbidly obese" yet. I thought I was overweight, but not badly so.
Then I stopped and took a good look at my BMI and where it should be, and decided to diet. I lost some weight myself, and then went to a doctor who prescribed a drug to help me. I ended up losing almost 70 lbs. I've gained about 20 of that back now, but I've been holding (or slowly slipping) for quite a few years now, and still want to lose again.
I look at old pictures of myself and I'm horrified at how fat I was. But at the time, I didn't see a problem.